1. Field of the Invention
The field of the invention is microsurgery, and particularly surgical tools for use therein, and more particularly microsurgical cutting tools.
2. Background of the Invention
Microsurgery is a broad term that refers to any surgical procedures performed under the magnification of a surgical microscope. Microsurgery is being employed to treat an increasing number of conditions, as it provides a number of benefits over conventional surgical techniques. Such advantages include avoidance of complications experienced during conventional, invasive procedures. Furthermore, microsurgery has enabled several new surgical protocols that simply could not be performed on a non-micro scale. As such, microsurgery represents an important, relatively new area of medicine that will continue to gain in applicability in the future. Already, microsurgical techniques are being employed in the areas of opthamology, neurosurgery, laparoscopic surgery, periodontal surgery, reconstructive surgery, reproductive surgery, etc.
Because of the importance of microsurgery to many different fields of medicine, a number of diverse microsurgical tools have been developed. One type of microsurgical tool is a cutting tool, i.e., a tool designed for cutting tissue. Microsurgical cutting tools require precise control of incision size and shape. Microsurgical cutting tools developed to date operate by a variety of different means, including laser means, cavitation means, and the like. For example, localized explosive evaporation and bubble formation generated by optical absorption and breakdown are used in intraocular surgery and other applications for soft tissue cutting and an electric discharge method for creating plasma-induced bubbles has recently been developed.
However, both optical and electric discharge techniques suffer from collateral damage to surrounding tissue. For example, while the vaporization and thermal tissue change due to high plasma temperature are confined to a small area at the probe tip dependent on energy and pulse duration, acoustic transients, bubble expansion and collapse can cause damage far beyond the application site. For example, three-dimensional expansion of the bubble formed inside blood vessels during the laser angioplasty may introduce damage to the walls of the vessel and cause restenosis similarly to the damage introduced during the baloon angioplasty. As discharge energies are reduced to limit collateral damage, the effectiveness of the tool for cutting tissue is also reduced.
As such, there is a continued need for the development of new microsurgical cutting tools that will localize not only the energy deposition but will also spatially confine the subsequent water flow, acoustic transients and other consequences of explosive evaporation. Of particular interest would be the development of a microsurgical cutting tool that provides for one-dimensional (axial) fast pulsating displacement of material with tight radial confinement, which may allow for precise dissection of tissue with minimal collateral damage.
3. Relevant Literature
U.S. patents of interest include: U.S. Pat. Nos. 5,288,288; 5,871,462; 5,944,686 and 6,039,726; as well as the patents reference therein. See also WO 99/33510 and WO 98/12974. Articles of interest include: Palanker, et al., “Dynamics of ArF Excimer Laser-induced Cavitation Bubbles in Gel Surrounded by a Liquid Medium,” Lasers in Surgery and Medicine, 21:294-300, 1997; Van Leeuwen, et al., “Excimer Laser Ablation of Soft Tissue: A Study of the Content of Rapidly Expanding and Collapsing Bubbles,” IEEE Journal of Quantum Electronics, Vol. 30, No. 5, 1994, pp. 1339-1345; Palanker, et al. “Electric discharge-induced cavitation: A competing approach to pulsed lasers for performing microsurgery in liquid media,” Proceedings of the SPIE, Vol. 2975, pp. 351-360; and Alfred Vogel, et al., “Intraocular Nd: YAG Laser Surgery: Light-Tissue Interaction, Damage Range, and Reduction of Collateral Effects,” IEEE Journal of Quantum Electronics, Vol. 26, No. 12, 1990, pp. 2240-2260.